The present invention relates generally to a method for color mapping geophysical data. More particularly, the present invention provides a method for combining two or more components of multicomponent geophysical data, so as to produce unique color displays of the combined components of the multicomponent geophysical data.
Color mapping of data involves a series of transformations employing a color coordinate system. Color mappings of geophysical data typically employ a one-dimensional color coordinate system wherein variations in one component of the geophysical data can be represented by varying shades of a selected color or by a spectrum of colors assigned to represent variations in the geophysical data. In fact, color mappings of geophysical data have generally plotted only the positive values of the geophysical data. Unfortunately, geophysical data sets are typically not limited to data having only positive values or data for which it is informative to represent both positive and negative values as scalar data by use of an offset. Exemplary of such geophysical data are seismic traces recorded during geophysical exploration which represent the earth's response to seismic energy imparted therein. Seismic traces represent one-dimensional data and are generally depicted in either the time-domain or frequency domain. Such seismic traces are complicated sinusoids having both positive and negative values. To more accurately interpret such seismic traces, knowledge of more than either positive or negative values is generally needed.
Because of the difficulty in uniquely mapping both the positive and negative measures of seismic traces, present color displays generally map only positive values of the seismic trace which can be decidedly biased or aliased in their representation of the complete seismic trace. Exemplary of such coloring mapping schemes are those proposed by Savit in U.S. Pat. No. 3,662,325; Lambright, et al., in U.S. Pat. No. 4,279,026; Rice in U.S. Pat. No. 4,467,461; and Anstey in Australian Patent Specification No. 54,809. Other color mapping schemes, such as described by Shock, et al., in U.S. Pat. No. 4,661,935, have been proposed to more accurately portray seismic phase angles. Moreover, none of these color mapping schemes provides a mechanism for uniquely combining two or more components of the multicomponent geophysical data, having both positive and negative values, in a single color display. This shortcoming is indeed unfortunate in view of current advances in geophysical exploration to collect, process and display multicomponent geophysical data.
A first approach to combining two or more components of multicomponent data on a single color display is described by Bucker in commonly owned, copending U.S. Pat. No. 4,843,599. In particular, Bucker describes a novel color coordinate system which is developed from an RGB (red, green, blue) Cartesian color coordinate system. Since the Bucker color coordinate system comprises sets of at least two color axes, mapping components of the multicomponent geophysical data in the Bucker color coordinate system can generally be achieved simply by assigning each component of the multicomponent geophysical data to a separate color axis and multiplication by an appropriate scaling factor. However, for those accustomed to evaluating variations in color in either the more conventional RGB or HLS (hue, lightness, saturation) color coordinate systems, evaluation of color displays employing the Bucker color coordinate system can be more cumbersome.
The present invention provides a method for producing continuous color displays of multicomponent geophysical data sets which overcomes the aforementioned limitations.